Segmental retaining walls (SRWs) have a firm presence within the retaining wall market and continue to grow in popularity, thanks to a marketing strategy known as co-op marketing. In co-op marketing, a licensor, its licensees, and distributors work together to promote the licensor's product. A licensor holds the patent for an SRW unit; licensees produce the units and pay royalties to the licensor; distributors pay the producer a royalty for the right to sell SRW units to installers. Segmental retaining wall block comes in either crib or modular units. Modular units contain internal steel reinforcement and must be placed by crane. Modular units ar significantly lighter and can be placed by hand or with a light crane.